Lambda Island is an island lying immediately north-west of Delta Island in the Melchior Islands, of the Palmer Archipelago in Antarctica. The island, the largest in the north-western part of the island group, was first roughly charted and named "Île Sourrieu" by the French Antarctic Expedition, 1903–05 under Jean-Baptiste Charcot, but that name has not survived in usage. The current name, derived from lambda, the 11th letter of the Greek alphabet, was given by Discovery Investigations personnel who roughly charted the island in 1927. The island was surveyed by Argentine expeditions in 1942, 1943 and 1948.